Polarity indicator



April 25, 1933.

H. FRIEDRICHSEN 1,905,697

POLARITY INDICATOR Filed Feb. 1950 1N VENTOR I wZZa-J HIS A TTORNEYPatented Apr. 25, 1933 UHTED STATES HEINRICH FRIEDRICHSEN, OFBERLIN-TREPTOW, GERMANY, ASSIGNOR T GENERAL ELECTRIC COMPANY, A.CORPORATION OF NEW YORK IPOLARITY INDICATOR Application filed February8, 1930, Serial No. 427,033, and in Germany June 21, 1929.

The present invention relates generally to electric discharge devices ofthe cathode glow type, and more particularly the invention relates tomeans and methods for adapting such devices to serve as polarityindicators.

The object of this invention is to provide a cathode glow lamp wherebythe polarity of an electrical circuit is indicated clearly andunmistakably. A further object of the invention is to provide such adevice of great simplicity and practicability.

In accordance with the object of the invention the cathode glow lamp isprovided with two rectangular fiat shaped electrodes placed in parallelpositions and'a stencil which is mounted on the vitreous bulb of suchdevice, said stencil having'a plus and a minus sign thereon, oneopposite each of the electrodes.

In the drawing accompanying and forming part of this specification anembodiment of the invention is shown for purposes of illustration, inwhich Fig. 1 is a side elevational view of the newand novel polarityindicator with the stencil shown in cross section and the positionthereof being shown by dotted lines.

Fig. 2 is a top view of the device along the line 22 of Fig. 1.

As shown in the drawing the new and novel polarity indicator consists oftwo rectangular plate electrodes 5, 0 arranged in parallel verticalpositions in the cylindrical chamber a of the lamp, said chamber ahaving a suitable gaseous atmosphere therein. Lead wires d, f sealed inthe stem g connect with said electrodes 6, a

respectively and are adapted to support said electrodes. Stencil h is asplit resilient cylinder having its inside diameter slightly less thanthe outside diameter of the bulb a so that it is held in position onsaid bulb a by the friction resulting from the pressure it exerts onsaid bulb a by reason of its elastic resiliency. On opposite walls ofsaid stencil h and opposite the fiat side of each of saidelectrodes 6, oare punctures 2', k in the shape of a plus and a minus sign,respectively.

Each electrode lead 03, f is connected to one of the two contact membersof the Edi-Swan socket illustrated. Lead d is connected to the positivecontact member and lead 7 is connected to the negative contact member.Thus when operating with 5 the right polarity a glow is produced aroundnegative electrode 0 which can be seen by looking through puncture la Nolight shines through puncture 2' as the positive electrode 6 has no glowand in addition shuts oil the light from the. glow around negf ativeelectrode 0. Thus the correct polarity is clearly indicated. l/Vrongpolarity is just as clearly and unmistakably indicated, for under wrongoperating conditions the positive electrode 6 glows and the light canonly be seen through the plussign 2' thus it becomes immediatelyapparent that the lamp is operating on wrong polarity, as such glowlampsonly show a glow around the negative electrode when operating on properpolarity.

Various changes in the device and in its various parts may be madewithout departing from the spirit of the invention; Stencil it may beattached to the insulated socket instead of to the lamp bulb as shown.Said stencil may be made of any suitable material 7 or have any suitableperforation therethrough; under certain circumstances it may consist ofa lacquer or other material. The 80 lamp bulb may be made in variousshapes, and any suitable socket may be used.

WVhat I claim as new and desire to secure by Letters Patent of theUnited States, is:

A polarity indicator consisting of an electric discharge device of thecathode glow type comprising a container, a' gaseous atmosphere therein,electrodes therein and a stencil mounted externally thereon, saidstencil being a split-ring, resilient shell having its inside diameterslightly less than the outside diameter of the container and having aplus sign opposite the flat side of the positive electrode and a minussign opposite the flat 5 side of thenegative electrode, said electrodesbeing plates mounted in coextensive parallel relation, one of saidplates being a shield to prevent light from the other plate from passingthrough'the lamp Wall in the direction of the first named plate.

In Witness whereof, I have hereunto set my hand this 23d day of January,1930.

HEINRICH FRIEDRICHSEN.

